The invention relates to a device and a method for machining, namely profiling tree trunks, comprising a first rotating machining tool which rotates about a first axis and has a first workpiece machining zone, and comprising a second rotating machining tool which rotates about a second axis and has a second machining zone in such a way that the first axis and the second axis are essentially offset by 90° in relation to one another and are oriented in an essentially perpendicular direction to the axis of the tree trunk.
The object of this machining of tree trunks is to cut out a rectangular wood-edged corner area from the tree trunk in order to herewith produce rectangular lateral edges for sideboards to be separated in a later machining step. For this cutting, saw blades are used on the one hand to produce an optimum lateral edge of the sideboard with aid of the saw cut, and, on the other hand, chopping knives to produce shavings with a defined shape which can be resold as a by-product of the tree trunk when cut out of the corner regions of the tree trunk.
The relevant prior art has been dealing with the technology of profiling for decades. Thus, for example, a device of this type for profiling tree trunks is described in DE-A 37 02 890 in which both rotating machining tools consist of combined tool heads which, on the one hand, hold saw-blade elements and, on the other hand, chopping knives.
An almost identical profiling device is known from DE-A 199 60 319 in which, however, the first rotating machining tool does not have any additional chopping knives but only comprises a circular saw blade. As a result, the machining volume machined by the chopping knives of the second machining tool is slightly greater than in the aforementioned device with two rotating chopping knives. However, the disadvantage of a first machining tool consisting of only one circular saw blade is that the split formed by the circular saw blade produces an instability in the machining zone for the second machining tool as the corner area to be cut out by the second machining tool is only connected to the tree trunk on one side, whereas the second side of the corner area is completely separated from the tree trunk by the saw cut. When this corner area which is only supported on one side by means of the chopping knives of the second machining tool is acted upon, due to the lack of support, the corner area tends to vibrate which makes the machining of this corner area with the second machining tool more difficult and clearly affects the result of this operation.
To prevent this spring-tongue-like oscillation, according to the subject matter of DE 199 60 319, this split is supported in the area which has just been sawed clear but not yet acted upon by the chopping knife of the second machining tool with aid of a splitting wedge which is secured on the machining device between the two rotating machining tools. The disadvantage of splitting wedges of this type can easily become stuck due to their thickness corresponding to the width of the saw cut and consequently interrupt the entire production process. If, due to the fact that they got stuck, the splitting wedges are also damaged or due to the fact they wear quickly, the splitting wedges must also be replaced which results in additional costs. If, due to wear, one wishes to delay the replacement of the splitting wedges a little, then this results in so-called endless streaks which are produced due to the fact that the corner area to be cut out by the chopping knife of the second machining tool no longer has adequate support and, as a result, the corner area can yield slightly downward in such a way that the chopping knife cannot remove the entire volume of the corner area to be cut out.